Tunable Relaxation Oscillator Circuit With Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing relaxation oscillators lack flexibility in tuning output frequency while maintaining temperature compensation, making them unsuitable for integrated circuits that require precise frequency control across a range of operating temperatures.
Innovation Solution
A tunable oscillator circuit with an adjustable reference current generator and capacitors, coupled with a control circuit, allows for precise tuning of the oscillator period across a wide range by adjusting capacitance and reference current, while maintaining a low temperature coefficient through offsetting temperature coefficients of circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the oscillator uses fixed reference current and fixed capacitance, then the circuit is simple, but the tuning flexibility is poor
Solution Approach 1:
The patent implements dynamic adjustability by introducing control circuits that can modify the reference current magnitude and capacitor connectivity based on tuning inputs. The reference current generator includes controllable current sources that can be adjusted in magnitude, and the capacitor circuit includes switches that can reconfigure which capacitors are connected in series or parallel, transforming a static circuit into a dynamically tunable one.
Solution Approach 2:
The patent changes key parameters (reference current magnitude and effective capacitance) to achieve tuning flexibility. By controlling the magnitude of the reference current through adjustable current sources and changing the effective capacitance through switchable capacitor configurations, the oscillator period can be tuned across a wide range while maintaining circuit manageability.
2Adaptability or versatility
If the oscillator is tuned across a wide frequency range, then the tuning range is significant, but the temperature stability deteriorates
Solution Approach 1:
The patent employs temperature compensation mechanisms that use feedback principles to counteract temperature effects. Temperature sensing circuits detect changes in operating temperature and adjust the reference current or capacitance values accordingly to maintain a stable oscillator period. The control circuits receive temperature information and modify tuning parameters to compensate for thermal drift.
Solution Approach 2:
The patent applies counterbalancing by introducing temperature compensation circuits that generate opposing effects to neutralize temperature-induced frequency drift. The compensation circuits are designed to produce frequency shifts in the opposite direction of temperature effects, effectively canceling out thermal instability and maintaining consistent oscillator performance across temperature variations.
3Measurement precision
If the oscillator period is tuned by adjusting reference current, then the tuning precision is good, but the temperature coefficient increases
Solution Approach 1:
The patent changes the approach by not only adjusting reference current magnitude but also modifying the effective capacitance value through switchable capacitor configurations. This dual-parameter adjustment allows precise tuning of the oscillator period while distributing the tuning burden, reducing the temperature sensitivity that would result from current adjustment alone.
Solution Approach 2:
The patent introduces temperature compensation circuits as intermediaries between the tuning mechanism and the oscillator core. These compensation circuits act as mediators that detect temperature changes and automatically adjust tuning parameters to offset thermal effects, thereby maintaining tuning precision while minimizing the temperature coefficient.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables stable and precise tuning of the oscillator period across a significant frequency range with minimal temperature variation, enhancing the oscillator's flexibility and applicability in integrated circuits.
Implementation Method 1
a capacitance of an adjustable capacitor that is operably coupled to the capacitive node
Implementation Method 2
A comparator having inputs operatively coupled to a reference voltage node and to the capacitive node generates a comparator output
Data Source
AI summary
A relaxation oscillator includes an adjustable reference circuit generator to produce a reference current which is applied to a charging circuit. The charging circuit is configured to charge a capacitive node as a function of the reference current and a capacitance of an adjustable capacitor that is operably coupled to the capacitive node. A comparator having inputs operatively coupled to a reference voltage node and to the capacitive node, generates a comparator output. A control circuit alternatively enables the charging circuit to charge the capacitive node and to discharge the capacitive node in response to changes in the comparator output. Also, the control circuit outputs and oscillator output signal have an oscillator period as a function of the adjustable capacitance and the adjustable reference current.